9.1.4.1 Signaling

When a condition is signaled, the most recent applicable activehandler is invoked. Sometimes a handler will decline by simply returning without a transfer of control. In such cases, the next most recent applicable active handler is invoked.

If there are no applicable handlers for a condition that has been signaled, or if all applicable handlers decline, the condition is unhandled.

The functions cerror and error invoke the interactive condition handler (the debugger) rather than return if the condition being signaled, regardless of its type, is unhandled. In contrast, signal returns nil if the condition being signaled, regardless of its type, is unhandled.